Which of the following is the correct match?

Options

A. Classical smog - `NO_(2)`
B. Photochemical smog - `SO_(2)`
C. Greenhouse gas - `CH_(4)`
D. Both (1) & (3)

Answer

To solve the question, "Which of the following is the correct match?", we will analyze the options provided in the context of environmental chemistry, specifically focusing on smog types and greenhouse gases.

### Step-by-Step Solution:

1. **Understand the Types of Smog:**
- There are two main types of smog: **Classical Smog** and **Photochemical Smog**.
- **Classical Smog** is a mixture of smoke and fog, typically found in cool and humid places. It contains sulfur dioxide and is characterized as reducing in nature.
- **Photochemical Smog** occurs in warm, dry, or sunny climates and is formed from unburnt hydrocarbons and nitrogen oxides. It is characterized as oxidizing in nature.

2. **Analyze the Options:**
- The question provides options that likely match types of smog with their respective components or characteristics.
- For **Classical Smog**, the correct component should be **sulfur dioxide**.
- For **Photochemical Smog**, the correct component should be **nitrogen oxides**.

3. **Evaluate the Given Matches:**
- If an option states that **Classical Smog** is matched with **Nitrogen Dioxide**, it is incorrect because Classical Smog should be associated with **Sulfur Dioxide**.
- If an option states that **Photochemical Smog** is matched with **Sulfur Dioxide**, it is also incorrect because Photochemical Smog should be associated with **Nitrogen Oxides**.

4. **Identify Greenhouse Gases:**
- Greenhouse gases include **methane (CH₄)**, **carbon dioxide (CO₂)**, **ozone (O₃)**, **water vapor (H₂O)**, and **nitrous oxide (N₂O)**.
- If one of the options correctly identifies **methane** as a greenhouse gas, this option is correct.

5. **Conclusion:**
- After analyzing the options, the correct match is the one that identifies **methane** as a greenhouse gas.

### Final Answer:
The correct match is the option that states **methane** is a greenhouse gas.

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